Commodore 1541-II - More about INPUT (Advanced)

but many programs cheat on safety a bit ana use
800 INPUT#5,NAME$,STREET$,CITY$
810 GOSUB 59990:REM CHECK FOR DISK ERRORS
This is done primarily when top speed in the program is essential, and there is little or no
risk of reading improper data from the file.
MORE ABOUT INPUT# (FOR ADVANCED USERS)
Troublesome Characters
After you begin using data files regularly, you may encounter two Basic error
messages more or less frequently. They are "STRING TOO LONG ERROR" and "FILE
DATA ERROR". Both are likely to halt your program at an Input# statement, but may
also have been caused by errors in a Print# statement when the file was written.
"STRING TOO LONG" ERRORS
A Basic string may be up to 255 characters long, although the longest string you can
enter via a single Input statement is just under 2 lines of text (4 on the VIC 20). This lower
limitation is due to the 88 character size of the Input buffer in Commodore's serial bus
computers. The same limit applies to Input# statements. If a single data element (string or
number) being read from a disk file into an Input# statement contains more than 87
characters, Basic will halt with a "STRING TOO LONG ERROR". To prevent this
error, be sure to limit each string to under 88 characters, and separate all file data items
with carriage returns (See the next section for a cure once the error has occurred.)
"FILE DATA" ERRORS
The other error message "FILE DATA ERROR" is caused by attempting to read a
non-numeric character into a numeric variable. To a computer, a number is the characters
0 through 9, the " + " an3 " - " signs, the decimal point (.), the SPACE character, and
the letter "E" used in scientific notation. If any other character appears in an Input# to a
numeric variable, "FILE DATA ERROR" will be displayed and the program will halt.
The usual causes of this error are a mismatch between the order in which variables are
written to and read from a file, a missing carriage return within a Print# statement that
writes more than one data item, or a data item that includes either a comma or a colon
without a preceding quotation mark. Once a file data error has occurred, you should
correct it by reading the data item into a string variable, and then converting it back to a
number with the Basic Val() statement after removing non-numeric characters with the
string functions described in your computer users manual.
COMMAS (,) AND COLONS (:)
As suggested before, commas and colons can cause trouble in a file, because they
delimit (end) the data element in which they appear and cause any remaining characters in
the data element to be read into the next Input# variable. (They have the same effect in an
Input statement, causing the common "EXTRA IGNORED" error message.) However,
sometimes we really need a comma or colon within a data element, such as a name written
as "Last, First". The cure is to precede such data elements with a quotation mark. After a
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